The present invention relates to an electrode extraction terminal for a unidirectional condenser microphone unit and a unidirectional condenser microphone unit. More specifically, the present invention is a technology relating to the electrode extraction terminal for a unidirectional condenser microphone unit which can easily change a directivity of a small lot member for a cardioid into that for a hyper cardioid, and the unidirectional condenser microphone unit comprising the electrode extraction terminal.
A condenser microphone unit is formed such that a vibration plate vibrating by a sound wave is opposed to a fixed pole through a spacer so as to have a function as a condenser which can change an electrostatic capacity according to a degree of a vibration of the vibration plate.
In that case, a specific structure of the condenser microphone unit is formed to have, for example, a structure shown in FIG. 8 of the application, wherein FIG. 3 of Japanese Patent Application Publication No. 2007-300268 is depicted. Namely, according to this figure, a condenser microphone unit 100 is formed as a whole by housing, a vibration plate 120 stretched in a diaphragm ring 121; a fixed pole 130 with sound holes 131 opposed to the vibration plate 120 by disposing a spacer which is not shown in the figure between the fixed pole 130 and the vibration plate 120; a pedestal (an insulation seat) 133 supporting a marginal portion of the fixed pole 130; an electrode extraction terminal 135 integrally combined with the pedestal (the insulation seat) 133; and a lock ring 136 screwed to a female screw of a unit case 101, inside the unit case 101 including a front acoustic terminal 102 on a front end face.
Specifically, the pedestal 133 made of an insulation material and the electrode extraction terminal 135 made of a conductive metal material in FIG. 8 are mutually formed as separate bodies, and are disposed inside the unit case 101 by integrally combining the pedestal 133 and the electrode extraction terminal 135.
Meanwhile, in using a microphone, there is also a case wherein it is more preferable that the directivity shows the hyper cardioid than the cardioid depending on a situation of collecting sound, and in order to meet such demand, there is proposed a condenser microphone of the Japanese Patent Application Publication No. 2007-300268.
Namely, the condenser microphone of the Japanese Patent Application Publication No. 2007-300268 has been proposed based on a point that if a distance between a front acoustic terminal and a back acoustic terminal becomes comparatively short, a sensitivity also declines, so that the directivity thereof can be made as the cardioid, and if the distance between the front acoustic terminal and the back acoustic terminal becomes comparatively long, a sensitivity for a bi-directivity increases, so that the directivity thereof can be made as the hyper cardioid.
In the condenser microphone of the Japanese Patent Application Publication No. 2007-300268, technical features thereof are that in a state wherein a microphone main body contains nothing in an air chamber provided at a front end portion thereof, in case the condenser microphone unit 100 is attached, the distance between the front acoustic terminal 102 and the back acoustic terminal becomes the longest, and the sensitivity for the bi-directivity increases. Accordingly, the directivity thereof can be made as the hyper cardioid, and if a separately prepared attachment is coaxially disposed inside the air chamber, the distance between the front acoustic terminal 102 and the back acoustic terminal becomes shorter than that in a case of the hyper cardioid, and the sensitivity also declines for that so as to allow the directivity thereof to be the cardioid.
However, in a case of the condenser microphone of the Japanese Patent Application Publication No, 2007-300268, after the attachment is separately prepared, the microphone main body is coaxially disposed inside the air chamber provided at the front end portion thereof so as to be the cardioid, and by removing the attachment, it can be changed to the hyper cardioid. Accordingly, there are inconveniences that a troublesome operation for changing the directivity is required so as to increase the number of members for that, and to raise a cost as well.
In view of the aforementioned problems of a conventional technology, the present invention has an object of providing an electrode extraction terminal for a unidirectional condenser microphone unit which can easily change the directivity thereof into the hyper cardioid by simply applying a sandblast to the small lot member suitable for the cardioid, and a unidirectional condenser microphone unit comprising the electrode extraction terminal.
Further objects and advantages of the invention will be apparent from the following description of the invention.